Required Testing for Hemp: Establishing Parameters and Action Limits

22 June 2021
hemp testing

Required Testing for Hemp: Establishing Parameters and Action Limits

Montpelier, VT - This blog continues the “Required Testing for Hemp” series from March 19, 2021 Required Testing for Hemp Crops and Hemp Products | Agency of Agriculture, Food and Markets . The Vermont Agency of Agriculture, Food and Markets’ Hemp Program reminds hemp growers and processors of their obligation to comply with the Vermont Hemp Rules including testing requirements that reduce risk and help protect the consuming public.  All hemp crops, hemp products and hemp-infused products must be tested and meet potency and contaminant action limits.  There is some flexibility when testing may occur.  Registrants may use this flexibility at their discretion so long as they maintain records that show compliance as outlined in the Vermont Hemp Rules.

In this update, the Hemp Program (the Program) goes beyond the required tests that are included in the Cannabis Quality Control Program (CQCP) and focuses on parameters and action limits.  Compliant results are represented by values that are at or below the stated action limit for the hemp crop, concentrate, product or infused product.  Federal law and other states may have additional regulations addressing testing, and contaminant thresholds impacting hemp crop and product distribution.

In establishing the parameters and action limits for Vermont Hemp Program registrants, the CQCP evaluated scientific sources and industry references.  The Program consulted resources from two scientific organizations that address cannabis and consumer safety, the American Herbal Pharmacopeia (AHP) and United States Pharmacopeia (USP).  The Program also reviewed literature from Cannabis Science and Technology (CST) an industry reference for advancing cannabis research, quality, and education.  The CQCP also considered parameters and action limits for hemp, and recreational and medical cannabis in other states. 

Parameters and Action Limits

Potency testing determines the concentration of cannabinoids present in a sample.  The Program requires laboratories to analyze and report the concentration of delta-9 THC and Total THC. Hemp Program registrants may request analysis of, or laboratories may report the concentration of other cannabinoids commonly found in cannabis such as CBD or CBG.

For the 2021 growing season, the Program continues to implement the “acceptable potency level” which is an action limit for delta-9-THC at 0.3% with an additional limitation of 1% or less for total theoretical THC, as measured on a dry weight basis. The acceptable potency level is subject to change in subsequent years of program administration to be in conformance with federal law.

Moisture or Water Activity analysis determines the amount of water in a sample or the relative chemical potential energy of water.  Moisture analysis is used to calculate dry weight potency and contaminant concentrations for crops and trim flower.  Processed trim flower also has action limits for moisture or water activity, to minimize/arrest microbiological growth on hemp in storage or when packaged for retail sale. 

Action limits for processed trim flower are 0.65 water activity or 13% moisture.  This action limit is consistent with limiting yeast and mold growth levels according to CST (T. Cundell, Cannabis Science and Technology 2(4), 36–49 (2019)) and is similar to cannabis requirements in other states.  USP method 1112 has a similar water activity setting of 0.60 ± 0.5 for nonsterile pharmaceutical products, such as tablets, powders, and ointments.

Microbiological analysis includes three different required tests: total aerobic bacteria, total combined yeast and mold (TCYM), and mycotoxins.  Bacteria and yeast/mold results can be indicative of overall crop quality. These two tests detect a wide range of bacteria and yeast/mold species, some that may be harmful to human health when consumed.  Certain mold species produce toxic compounds called mycotoxins that are harmful when consumed at unsafe levels. These include Ochratoxin A, and Aflatoxin B1, B2, G1, and G2.

The Program’s action limits for Total Aerobic Bacteria and TCYM for hemp follow AHP guidelines for orally consumed botanicals (American Herbal Pharmacopoeia (2014 rev) Cannabis Inflorescence Quality Control Monograph).  Sixteen states use similar TCYM limits for hemp, recreational or medical cannabis. 

Several states including Massachusetts and Colorado apply mycotoxin limits of 20 parts per billion (ppb) in their hemp, recreational or medical cannabis programs. The Food and Drug Administration (FDA) also has a limit of 20 ppb for Aflatoxin B1 in foods.  The Program set similar action limits for mycotoxins. 

Total combined yeast and mold action limits for trim flower are currently being evaluated by the Program and are not being enforced.  A registrant must still test for TCYM for each product process lot and as provided in the Vermont Hemp Rules.

 Heavy Metals analyses for Arsenic, Cadmium, Lead, and Mercury are required because they are present in the environment and can be taken up by the cannabis plant.

The Program’s action limits on heavy metals in hemp products and concentrate align with medicinal smoke-able cannabis and concentrate limits for Colorado, Massachusetts, and Canada.  

The Program’s action limits for heavy metals in soil are based on New York State Department of Environmental Conservation guidelines for unrestricted soil use. Guidance on interpreting total heavy metal soil tests conducted by the University of Vermont can be found here,

Pesticide testing includes 15 compounds, none of which are allowed for use on hemp crops.  The Program considered many resources when developing its pesticide parameter list including requirements in other states for cannabis.  The action limit for pesticides is the same whether tests are conducted on harvest lots, hemp concentrates, hemp products or infused products.

The Program reviewed levels set by several states and Canada.  California’s action levels for inhalable cannabis and cannabis products, was closely followed (California Department of Pesticide Regulation memo (2016) Recommended Guidelines for Pesticide Residue in Processed Cannabis and Cannabis Products). California in turn, referenced pesticide guidance residue levels (GRL) for tobacco from CORESTA (Cooperation Centre for Scientific Research Relative to Tobacco (2016, updated 2020) The Concept and Implementation of CPA Guidance Residue Levels).

Residual solvents are considered contaminants when they are present in a finished product and may be harmful to the consumer.  Solvent-based extraction techniques are common in both primary botanical and secondary processing, including ethanol winterization of CO2 extractions. The Program considered parameters from USP method 467 Residual Solvents, cannabis concentrate or infused products solvent contaminant lists from other states including California and Oregon, and its own research on solvents used for extraction and laboratory processes.

 The Program established its action limits based on USP method 467 Residual Solvents for its concentrate and edible infused products. Based on its research other states also appear to use the USP 467 action limits.  


A Hemp Program registrant may consider remediation steps to manage exceedances of action limits. Please consult with the Program when considering remediation strategies.  After a remediation step hemp crops, concentrate or product, including trim flower, must be resampled and retested.  These test results must be maintained by registrants to show compliance with Program action limits.     

Please refer to the Vermont Hemp Rules to understand requirements for analytical testing for potency and contaminants.  The Rules also include requirements for labels and which records or test results must be kept by registrants from seed to shelf, .

These testing requirements and hemp potency and contaminant action limits can also be found here, Specifically, table 2 lists testing requirements, and tables 3 through 8 list action limits for the hemp crop or product compliance. 

Questions about the requirements for hemp testing can be directed to Cannabis Quality Control Program Compliance Specialist, Bob Shipman: , or  


Contact Information

Agency of Agriculture, Food & Markets

116 State Street
Montpelier, Vt 05620-2901


Program Contacts

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